In September 1861, Wright became a brigadier general in the Union army. In 1862, he was placed in command of a division, which was defeated at Secessionville, South Carolina. After this, the War Department assigned Wright to command the Department of the Ohio. Wright maintained his command of the Department of the Ohio until 1863, when he took command of a division in the VI Corps of the Army of the Potomac. He served at Gettysburg, Rappahannock Station, Mine Run and the Wilderness. When Sedgwick was killed, he was promoted to major general, and he took over command of the VI Corps. In July 1864 was sent hurriedly to Washington, where he helped repel a Confederate raid. From August to December 1864, he fought under Sheridan in the Shenandoah Valley campaign. He returned to the Army of the Potomac with the VI Corps in early 1865 during the siege of Petersburg.